1. Field of the Invention
The present invention relates to a powertrain for driving a hybrid type motor vehicle comprising a powertrain that uses, alone or in combination, as a traction/propulsion drive, an internal-combustion thermal engine with a speed variation device, and a rotary electric machine connected to an electric source, such as one or more batteries.
This combination has the advantage of optimizing the performances of the vehicle, which notably reduces the discharge of emissions to the atmosphere and decreases the fuel consumption.
2. Description of the Prior Art
Thus, when a vehicle of the above type is to be driven with a high torque over a wide speed range while limiting exhaust gas and noise generation, as in an urban site, the electric machine is preferably used for driving this vehicle.
On the other hand, the thermal engine is used for driving this vehicle for uses where a high driving power and a wide operating range are required.
A hybrid vehicle has also been proposed, notably in U.S. Pat. No. 6,344,008, wherein part of the speed variation device comprises an epicyclic gear train with a crown, a sun gear and a planet gear carrier for driving the vehicle through its drive axle.
In this type of epicyclic gear train, it is difficult to control the direction of rotation of the various elements, which can go against the desired direction. This leads to parasitic stresses and load torques that interfere with the smooth running of the epicyclic gear.
As better described in French Patent Publication No. 2 955 165, corresponding to US 2011/0172044 A1, filed by the Assignee, the speed variation device is improved by configuring the epicyclic gear train with one-way couplings and controlled clutches, and by arranging a variable speed transmission device between the electric machine and the axle of the vehicle.
With a view to continuous improvement, the Assignee has further perfected this variable speed transmission device by simplifying it while making it possible for the vehicle to be driven by the electric machine with different gear ratios.